Torsten Kroeger

Stanford Artificial Intelligence Laboratory

Sensor Data Fusion

This research has been conducted at the Institut für Robotik und Prozessinformatik at the Technische Universität Braunschweig, Germany.

Motivation: Improving Force Control

This research focusses on sensor fusion in robotic manipulation: 6D force/torque signals and 6D acceleration signals are fused. The potential of six-axis acceleration sensors in the field of robotic manipulation applications is quite high and most of it has not been used yet: When considering six-joint industrial manipulators with six-axis force/torque and six-axis acceleration sensing, many new possibilities arise:

  • all ten inertial parameters of any object can be identified and objects can be recognized based on these parameters,
  • position control behavior can be improved,
  • actuator positions and measured acceleration signals can be fused in order to estimate linear and angular velocities,
  • the acceleration signals can be used estimate actuator position signals with the aim to detect encoder/resolver failures,
  • non-contact forces can be extracted and force control performance can be improved, and/or
  • visual servo control methods can use acceleration signals to become more robust.

Separation of Contact and Non-Contact Forces/Torques

Details may be found in any of the papers listed below. One very clear result is illustrated by the following figure. The left diagrams show a robot motion of an acceleration phase, a short phase of constant velocity, and a deceleration phase to bring the end-effector back to zero velocity. During the whole motion, no environmental contact occurs. The right diagrams show the reverse motion of the left diagrams, but here, the end-effector hits some object. Based on the measured force signal only (top right diagram), this can hardly be detected. The estimated contact force signal, which bases on the measured acceleration signal, lets us clearly see the contact (bottom right diagram).

  • Left: Estimated non-contact forces without environmental contact. Right: Estimated non-contact forces with environmental contact (click to enlarge). Left: Estimated non-contact forces without environmental contact. Right: Estimated non-contact forces with environmental contact (click to enlarge).

 

Please refer to the following publications:

  • On-Line Estimation of Inertial Parameters Using a Recursive Total Least-Squares Approach.
    In Proc. of the IEEE/RSJ International Conference on Intelligent Robots and Systems, pp. 3845-3852, Nice, France, September 2008. BibTeX

    @inproceedings{Kubus:08,
    	author = {D.~Kubus and T.~Kr{\"o}ger and F.~M.~Wahl},
    	title = {On-Line Estimation of Inertial Parameters Using a Recursive Total Least-Squares Approach},
    	booktitle = {Proc. of the IEEE/RSJ International Conference on Intelligent Robots and Systems},
    	month = {September},
    	pages = {3845--3852},
    	address = {Nice, France},
    	year = {2008}
    }
    			
  • Multi-Sensor Integration and Sensor Fusion in Industrial Manipulation: Hybrid Switched Control, Trajectory Generation, and Software Development.
    In Proc. of the IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems, pp. 411-418, Seoul, South Korea, August 2008. BibTeX

    @inproceedings{Kroeger:08e,
    	author = {T.~Kr{\"o}ger and F.~M.~Wahl},
    	title = {Multi-Sensor Integration and Sensor Fusion in Industrial Manipulation: {H}ybrid Switched Control, Trajectory Generation, and Software Development},
    	booktitle = {Proc. of the IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems},
    	month = {August},
    	pages = {411--418},
    	address = {Seoul, South Korea},
    	year = {2008}
    }
    			
  • Improving Force Control Performance by Computational Elimination of Non-Contact Forces/Torques.
    In Proc. of the IEEE International Conference on Robotics and Automation, pp. 2617-2622, Pasadena, CA, USA, May 2008. BibTeX

    @inproceedings{Kroeger:08,
    	author = {D.~Kubus and T.~Kr{\"o}ger and F.~M.~Wahl},
    	title = {Improving Force Control Performance by Computational Elimination of Non-Contact Forces/Torques},
    	booktitle = {Proc. of the IEEE International Conference on Robotics and Automation},
    	month = {May},
    	pages = {2617--2622},
    	address = {Pasadena, CA, USA},
    	year = {2008}
    }
    			
  • 12D Force and Acceleration Sensing: A Helpful Experience Report on Sensor Characteristics.
    In Proc. of the IEEE International Conference on Robotics and Automation, pp. 3455-3462, Pasadena, CA, USA, May 2008. BibTeX

    @inproceedings{Kroeger:08a,
    	author = {T.~Kr{\"o}ger and D.~Kubus and F.~M.~Wahl},
    	title = {12D Force and Acceleration Sensing: {A} Helpful Experience Report on Sensor Characteristics},
    	booktitle = {Proc. of the IEEE International Conference on Robotics and Automation},
    	month = {May},
    	pages = {3455--3462},
    	address = {Pasadena, CA, USA},
    	year = {2008}
    }
    			
  • Force and Acceleration Sensor Fusion for Compliant Manipulation Control in Six Degrees of Freedom.
    Advanced Robotics. Vol. 21, No. 14, pp. 1603-1616, November 2007. BibTeX

    @article{Kroeger:07,
    	author = {T.~Kr{\"o}ger and D.~Kubus and F.~M.~Wahl},
    	title = {Force and Acceleration Sensor Fusion for Compliant Manipulation Control in Six Degrees of Freedom},
    	journal = {Advanced Robotics},
    	volume = {21},
    	number = {14},
    	month = {November},
    	pages = {1603--1616},
    	year = {2007}
    }
    			
  • On-line Rigid Object Recognition and Pose Estimation Based on Inertial Parameters.
    In Proc. of the IEEE/RSJ International Conference on Intelligent Robots and Systems, pp. 1402-1408, San Diego, CA, USA, October 2007. BibTeX

    @inproceedings{Kroeger:07c,
    	author = {D.~Kubus and T.~Kr{\"o}ger and F.~M.~Wahl},
    	title = {On-line Rigid Object Recognition and Pose Estimation Based on Inertial Parameters},
    	booktitle = {Proc. of the IEEE/RSJ International Conference on Intelligent Robots and Systems},
    	pages = {1402--1408},
    	month = {October},
    	address = {San Diego, CA, USA},
    	year = {2007}
    }
    			
  • 6D Force and Acceleration Sensor Fusion for Compliant Manipulation Control.
    In Proc. of the IEEE/RSJ International Conference on Intelligent Robots and Systems, pp. 2626-2631, Beijing, China, October 2006. BibTeX

    @inproceedings{Kroeger:06c,
    	author = {T.~Kr{\"o}ger and D.~Kubus and F.~M.~Wahl},
    	title = {{6}{D} Force and Acceleration Sensor Fusion for Compliant Manipulation Control},
    	booktitle = {Proc. of the IEEE/RSJ International Conference on Intelligent Robots and Systems},
    	address = {Beijing, China},
    	month = {October},
    	pages = {2626--2631},
    	year = {2006}
    }